With the protein displayed in wireframe, color chain.
Select hetero-ligand, display as sticks, and color CPK.
Examine the structure of the geranyl pyrophosphate
substrate, with its branched hydrocarbon chain.

Now display the ligands as spacefill. Where are the magnesium ions relative to the substrate? What role
might they have?Try to identify acidic enzyme residues that also interact with the magnesium.